run travis-ci tests on emulator

This is my collection of hacks to make travis-ci more reliably run the
test suite in an emulator.  It also updates the SDK tools to the latest
version to make sure things are working there.

Author: eighthave

.travis.yml

@@ -2,15 +2,44 @@
 language: android
 jdk: oraclejdk7
 
+env:
+  global:
+    # switch glibc to a memory conserving mode
+    - MALLOC_ARENA_MAX=2
+    # wait 5 minutes for adb to connect to emulator. Travis-ci cancels a
+    # stalled build after 10 minutes, so this should be shorter than that so
+    # there is time for the build to report the error.
+    - ADB_INSTALL_TIMEOUT=5
+
 android:
   components:
-     - android-22
-     - build-tools-22.0.1
-     - extra-android-m2repository
+    - tools
+    - platform-tools
+    - extra-android-m2repository
+    - build-tools-22.0.1
+    - android-22
+  licenses:
+    # only approve the Android software licenses, they match sources
+    # the Google licenses mean proprietary software with binary blobs
+    - 'android-sdk-preview-license-52d11cd2'
+    - 'android-sdk-license-.+'
 
 sudo: false
 notifications:
   email: false
 
 script:
-  - ./gradlew clean build
+  # 'assemble' everything and run all checks that do not require a device/emulator
+  # first with the wrapper, then with the system gradle
+  - ./gradlew clean build
+  - gradle clean build
+  # start the emulator after the build to conserve memory
+  - echo no | android create avd --force -n test -t android-21 --abi armeabi-v7a
+  - emulator -avd test -no-skin -no-audio -no-window &
+  - android-wait-for-emulator
+  - adb shell input keyevent 82 &
+  # now run the tests that require a device/emulator
+  - gradle connectedCheck
+
+after_failure:
+  - find * -name lint-results.xml | xargs cat